I know there are a bunch of R22 alternatives out there. I just want to know which one has the best miscibility with the existing oil (I'm guessing mineral?) and can be purchased with a 609 certification. Temperature curve is not important - this is going into a cooling unit on a milling machine. The unit is just optional for cooling the mechanicals. I suppose I could convert to R134a but I'd really rather not have to flush.

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08 W251 R350
97 W210 E320
91 W124 300E
86 W126 560SEL
85 W126 380SE Silver
85 W126 380SE Cranberry
79 W123 250
78 W123 280E
75 W114 280